Haven't done the Manta dive yet but it's on my list. Concur that it sounds amazing.
So that might take care of you right there.
Cathedrals on Lanai (you get there from dive shops on Maui) is also listed as a good dive. ^
When my wife and I tried for it in November, the Maui Dive Shop screwed everything up. Dive boat had maintenance issues, no backup boat, not other options and so on. It really was a bad experience, and as a result, I'd tell folks to avoid MDS.
There are other dive shops and dives on Maui (I'm a fan of Molokini Crater's backwall.), so Maui is a possibility for you.
Just remember your 24 hour interval between diving and flying.
Enjoy!